Overlay of histograms in panels in QCG

Dear experts,

Is it possible to overlay 1D histograms in the QC GUI in a single panel? This would be used quite often when monitoring certain observables i.e. per subdetector. If not is there a chance that this feature could be added? I would expect JSROOT should support multiple histograms per panel.

Thanks in advance!



Dear Markus,
not sure if it satisfies you but one can use TCanvas to store multiple objects.

Dear @sbysiak,

Thanks for your reply!

Do I understand correctly that in such cases we would store a TCanvas as monitoring object in the QC task in the QCDB which can be displayed in the way it was stored with QCG.

Doing this in the task would really be ideal, but could this be done in an aggregator? I would think so.



Yes, TCanvas can be used as MO, see for instance qc/FT0/MO/TriggerRates/cRates.
This one I created in postprocessing task (which is kind of aggregator) or you mean quality aggragation (https://github.com/AliceO2Group/QualityControl/blob/master/doc/ModulesDevelopment.md#quality-aggregation) ?


Thank you Sebastian, it is what I would have proposed.
@mfasel If you have an example of such an overlay histogram in a ROOT file we could see if JSROOT can handle it somehow. However, just using a canvas in such a case seems to be ok.

You can produce a TCanvas in a task.

Aggregators are for qualities. I presume that you refer to post-processing ?

Hi @bvonhall,

Thanks for your reply! As example, we would like to monitor in this layout https://qcg-test.cern.ch/?page=layoutShow&layoutId=60d06f528c6a467ab0d83e5d&layoutName=Shifter_Raw_EMCAL the left and middle plot (EMCAL and DCAL min ADC) in the same panel.